Magnetic fields & induction worksheet with answers

Free printable Magnetic fields & induction worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy

A long straight wire carries a current of 12 A. Find the magnetic flux density B at point P, 15 cm from the wire.

I = 12 Ar = 15 cmμ₀ = 4π × 10⁻⁷ T·m/A

B = µT

2.Easy

An electron moves at 2 × 10⁶ m/s at an angle of 60° to a uniform magnetic field of 0.02 T. Find the magnitude of the magnetic force F on it.

|q| = 1.602 × 10⁻¹⁹ Cv = 2 × 10⁶ m/sB = 0.02 Tθ = 60°

F = fN

3.Medium

A circular loop lies in a uniform magnetic field pointing out of the page. The field strength is increasing. Click the direction of the induced current in the loop as seen in the drawing.

B: out of the pagedB/dt > 0

1clockwise
2counterclockwise

4.Medium

A coil of 500 turns has an area of 50 cm². A uniform field perpendicular to the coil rises steadily from 0 T to 0.6 T in 500 ms. Find the average induced emf ε.

N = 500A = 50 cm²B: 0 T → 0.6 TΔt = 500 ms

ε = V

5.Hard

A deuteron passes undeflected through a velocity selector with crossed fields E = 2 × 10⁵ V/m and B₁ = 0.05 T. It then enters a second region with only a magnetic field B₂ = 0.25 T, at right angles. Find the radius r of its path there.

E = 2 × 10⁵ V/mB₁ = 0.05 TB₂ = 0.25 Tm = 3.344 × 10⁻²⁷ kg|q| = 1.602 × 10⁻¹⁹ C

r = cm

6.Hard

A long air-core solenoid has 500 turns, a length of 25 cm and a diameter of 5 cm. Find its self-inductance L.

N = 500l = 25 cm⌀ = 5 cmμ₀ = 4π × 10⁻⁷ T·m/A

L = mH

Answer key

1. B = 16 µT
2. F = 5.549 fN
3. clockwise
4. ε = 3 V
5. r = 33.4 cm
6. L = 2.467 mH

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